Massage device



April 14, 1959 J. WAHL Re. 24,630

' MASSAGE DEVICE I Original Filed April 1. 1953 II II J, I '1 I 6, A

L l E g I l I:

M I n 7 United States Patent MASSAGE DEVICE Leo J. Wahl, deceased, lateof Sterling, 111., by John F. Wahl, Robert L. Wahl, and Warren P. Wahl,executors, Sterling, 111.; said Leo J. Wahl assignor to Wahl ClipperCorporation, Sterling, 11]., a corporation of Illinois Original No.2,768,621, dated October 30, 1956, Serial No. 346,108, April 1, 1953.Application for reissue October 24, 1958, Serial No. 769,527

4 Claims. (Cl. 128-41) Matter enclosed in heavy brackets appears in theoriginal patent but forms no part of this reissue specification; matterprinted in italics indicates the additions made by reissue.

My invention relates to a [massage device oi] vibrw tory unit which maybe used in massaging devices such as the type adapted to be mounted onthe back of an operators'hand. Such a device transmits vibrations to theoperator's fingers which are in turn applied to the desired parts of thebody for massage purpose.

My US. Patent No. 1,832,437 illustrates one of my prior massage devices,while my earlier US. Patent No. 1,818,287 (issued on a later filedapplication) shows the device equipped with a hand mounting attachment.My present invention relates to the same general type of device.

The massage device of this invention and those of my prior. patents isof the type which uses an electromagnet and. an armature to produce thedesired vibrations. It comprises an electromagnet of substantial massand an armature mounted in efiective relation with the electromagnet.The latter is energized by alternating or pulsating current and thearmature is successively attracted and released by the electromagnet toproduce vibrations suitable for massage. The armature is the elementwhich is associated with the operators hand.

Electromagnetic massage devices of this character necessarily are tunedto vibrate at a resonant frequency which is a multiple of the frequencyof the alternating or pulsating current applied to the electromagnet.Usually the tuned frequency of the device is related to the frequency ofthe applied current by a factor of [one] two, although other factors [oftwo or more] are possible. For example in a 60 cycle A.C. current, thetuned or resonant frequency of the device would be 120 cycles persecond.

As is well known, a vibrating device of this character is tuned byassigning proper mass to both the electromagnet and the armature, and byproviding a matching resilient connection between the two. Properselection of these variables, of course, requires consideration of thevalue of the voltage applied to the electromagnet as well as itsfrequency.

Prior massage devices [of this character] have been tuned to vibrate atresonant frequency under no load conditions such as when the handcarried and hand operated device is not mounted on the hand of anoperator, or is held loosely. This means that the vibrational energydelivered by the device is substantially a maximum when the device isunmounted. It other words, when [the] a hand carried massaging device isheld loosely in the hand, i.e. under no load conditions and the currentis turned on, the device [vibrates] will vibrate with maximum energy ina manner which is regarded as somewhat objectionable. This is apractical shortcoming of the electromagnetic device.

Competing massage devices utilize a rotary motor with an eccentric toproduce vibratory action. This type of massage device is substantiallyfree of the aforesaid objection present in the electromagnetic type.Despite the Re. 24,630 Reissued Apr. 14, 1959 fact that the rotary motortype is considerably more expensive to manufacture than theelectromagnetic type, the former is preferred by many because of itsfreedom from objectionable vibration when held loosely in the hand.

One object of my invention, therefore is to provide an electromagnetictype massage device which is substantially free of objectionablevibration under no load conditions or in the case of a hand carried andhand operated massaging device, when unmounted.

Another object of the invention is to provide an improvedelectromagnetic type massage device which can be constructed at a costwhich does not exceed that of present electromagnetic type devices. Thiscost, as previously mentioned, is substantially below that of competingmotor driven devices.

My invention contemplates the provision of an electromagnetic typemassage device which is substantially the same with those shown in myaforesaid prior patents with the exception that my present device istuned in accordance with a new principle. Rather than tuning the devicefor resonant operation when unmounted or under no load, in accordancewith this invention, I tune the device for resonant operation when itoperates under a load or is mounted on the operators hand. In otherwords, I take into consideration the efiect of the load or the mass ofthe operators hand in designing the device for resonant operation. As aresult, the device is substantially detuned and non-vibratory whenunmounted. This, of course, eliminates the aforesaid objection to priorelectromagnetic type massage devices.

Other objects, advantages and details of my invention will appear as thedescription proceeds, reference being bad to the accompanying drawingwherein one form of the invention is shown. It is to be understood thatthe description and drawing are illustrative only, and that the scope ofthe invention is measured by the appended claims.

In the drawing, the single figure is a view in side elevation, partlybroken away, of a massage device embodying my invention.

In one common form, an electromagnetic type massage device includes anE-shaped core 5, but the shape of the core is not critical. [an] Anenergizing coil 6 is on the core, and an armature 7 is fixed to thecasing 10 in effective relation to the face of the core. In addition, aresiliently biased hinge 8 [interconnecting] interconnects the armatureand the core directly or indirectly so that the electromagnet includingthe core 5 and the coil 6 are resiliently and pivotally mounted insidethe casing 10. and] Furthermore looped coil springs 9 are provided andcomprise means.[9] for mounting the armature on the back of an operatorshand, when the device is to be hand carried and hand operated. The coreand coil, the electromagnet, have substantial mass and may be regardedas the inertial portion of the device against which the armature ormoving portion reacts.

In a more complete form, the device includes a casing 10 which ismounted on the armature and encloses the core, coil, armature, andbiased hinge arrangement. The shape of the casing is not critical andmay be suited to the purpose for which the vibrating unit is to be used.For example when it is to be used in a vibratory pillow massagingdevice, the casing may be provided with large spaced parallel surfaces.

Regardless of the ultimate purpose for which the vibrating unit is to beused, the hinge arrangement 8, [in the usual form of the device]comprises a leaf spring of predetermined stiiiness which intermediateits ends is curved to provide a right angle'bend, one end of the springbeing attached to core 5 and the other to armature 7.

In the practice of the present invention, the biased hinge 3 or leafspring arangement 8.- whichinterconnects the armature and the coredirectly or indirectly has a stillness which [exceeds by about 8%-12%the stiffness required to produce-resonant vibrationwhen the devicejisunmounted] causes'the tune ofthe device to be at least from 8% to 12%aboveresonance, i.e-. at least over 130 cycles per second since theresonant frequency is 120 cycles per second when a 60 cycle current isapplied to the coil, and a value from at least 8 to 12% higher than 120cyclesis at least 130 cycles. This extra stiffness-provides asufficiently detuned condition so that the device is substantiallynon-vibratory under no load conditions or when not applied to the hand.It is true that low amplitude force vibrations do occur, but the energydeveloped thereby is so low that it is wholly unobjectionable.

When a device tuned as aforesaid is applied to an operators hand, or isunder load, the mass of the hand added to that of the armature'or theeflect of the load thereon establishes a new relationship between theparameters of the system. The new relationship is such that the deviceis then tuned to vibrate at resonance. Thus, the vibratory energy outputof-thedevice when mounted is at maximum, and the device operates atdesired efficiency.

A device constructed in-accordance with my invention, in addition toeliminating the objectionable vibrations which occur when the device isnotv under load or is unmounted, in fact operates with improvedefliciency when it operates under load conditions or is'mounted on thehand. This is because prior devices experienced a certain amount ofdetuning and corresponding loss of efliciency when-mounted foroperationor when under load.

From the above descriptionit is thought that the construction andadvantages of my invention will be readilyapparent to those skilled inthe art. Various changes in in detail may be made without departing fromthe spirit or losing the advantages of the invention.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

l. A [massage device for attachment to the back of an operators hand]vibratory unit comprising [an E- shaped] a core, an energizing coil onsaid core, an armature in ettective relation to the face of said core, aleaf spring interconnecting said armature and said core so thatsaid-corecan resiliently vibrate with respect to said arma' ture, [andmeans mounting said armature to the back of an operators hand] thestiffness of [the] said leaf spring [exceeding by about 8%12% thestiffness of a spring required to produce resonant vibrations when thedevice is not applied to the hand] causing the tune of the core andthecoil mounted thereon to be at least 8% above the resonance under noload so thatthedevice is. substantially non-vibratory under no load, butclose enough. to resonance so that [whereby] the device, [produces] canproduce resonant vibrations [when applied tojthehand and issubstantially non-vibratory when not applied to the hand] under load.

2. A massage device for attachment to the back of an operators handcomprising a core, an energizing coil on said core, an armature ineffective relation to the face of said core, a biased hingeinterconnecting said armature and said core. so that said core canresiliently vibrate with respect to said armature, and means mountingsaid armature to the back of an operators hand, the stifiness of thebias of said hinge [exceeding by about'8% l2% of the stiffness of a biasrequired to produce resonant vibration] causing the tune of the core andcoil mounted thereon to beat least 8% above resonance when the device isnot applied to the hand so that the device issubstantiallynon-vibratory, said tune close enough to resonance so that [whereby] thedevice [produces] can produce resonant vibrations when applied to thehand. [and is substantially non-vibratory when not applied to the hand]3; The apparatus set forth in claim 1 wherein the tune of the core andthe coil mounted thereon is at least 12% above resonance under no load.

4. The apparatus set forth in claim 2 wherein the tune of the coreand-coil mounted thereon is at least 12% aboze resonance when the deviceis not pplied to the hon Dremel July 18, 1933 Wahl Sept. 1 5,.1936

